Huttunen et al retrieval of aerosol optical depth from surface solar radiation measurements the current forcing of anthropogenic aerosol. Thanks go to aeronet for providing aerosol optical depth data and fine mode. Spatiotemporal variability of aerosols over east china. Aerosol optical depth measurements by airborne sun. Pdf merging regional and global aerosol optical depth records. Bayesian merging of misr and modis aerosol optical depth. Aerosols released into the atmosphere from anthropogenic activity cars, industry and natural events fires, dust storms affect human health, reduce visibility, and alter earths radiation budget. In other words, particles in the atmosphere dust, smoke, pollution can.
The air mass backtrajectory clustering analysis was combined with aerosol optical depth aod of fine mode, coarse mode and fine mode fraction in order to evaluate the longrange effects of transportation patterns of trajectories for the ground. Merging regional and global aerosol optical depth records. Though we only looked at feature optical depth values, the same approach can be taken for other data in the level 2 aerosol. Bell, c and petros koutrakis a a exposure, epidemiology, and risk program, department of environmental health, harvard school of public health, boston, ma 02215. Pnas plus microphysical effects determine macrophysical. Pdf merging regional and global aerosol optical depth. However, increasing the data coverage by merging the dt and db merged aod product has recently become the focus of research.
Several approaches were then investigated to merge the aod records from different satellites and. Use was made of groundbased observation, chemistrytransport models, and satellite. Aerosol optical depth over land from avhrr pathfinder. The tcap data set will be used to evaluate regional and global models. Merging regional and global aerosol optical depth records from. In other words, particles in the atmosphere dust, smoke, pollution can block sunlight by absorbing or by scattering light. Merging aerosol optical depth data from multiple satellite. Aerosol optical depth michigan technological university.
Will continue to merge the responsibilities across the. For example, the effect of changes in the current aerosol emissions on climate depends on the background aerosol load during the preindustrial era e. Retrieval of aerosol optical depth from surface solar. These data allow the optical depth representing the aerosol amount of coarse and fine radius p1. Aerosol optical depth aer can be expressed as function of wavelength through angstrom s equation. The aerosol algorithm is applied to every pixel at moderate resolution 0.
Aerosol optical depths typically decrease with increasing wavelength and are much smaller for longwave radiation than for shortwave radiation. Comparison of aerosol optical thickness with in situ. Use of satellitebased aerosol optical depth and spatial. Collection 5 introduced the deep blue algorithm for retrieval of aerosol optical depth aod over bright arid surfaces hsu et al. Depending upon their size, type, and location, aerosols can either cool the surface, or warm it. Retrieval of aerosol optical thickness over land surfaces. The aerosol optical depth after the middle of august is. Modis dark target products collection 6 and onward to. In chemistry, a closely related quantity called absorbance or decadic absorbance is used instead of optical depth. Exploring aerosol optical thickness using modis satellite.
Recently, a new technique to converting visibility measurements to aerosol optical depth aod has been developed on a stationtostation basis lin et al. Taking the moderate resolution imaging spectroradiometer modis remote sensor data as the data source, the aerosol optical depth of shanghai area on december 6, 20 is inversed from the use of second simulation of satellite. Discrepancies exist between aerosol optical depth aod products due to differences in their. Cooler colors in this image indicate lower values of the longwave radiative flux than normal, and hence more and higher clouds. Constraints used in the retrieval of aerosol optical thickness 22 as mentioned above, the separation of aerosol scattering and land surface reflectance requires additional information. The aerosol particle size parameter is provided only over ocean. Aerosol optical depth and burden from large sea salt. The negative slope or first derivative of aot with wavelength in logarithmic scale is known as the angstrom parameter.
Trends in aerosol optical depth over indiantrends in. The key quantity they report is aerosol optical depth aod, a measure of the amount of light that aerosols scatter and absorb in the atmosphere and generally prevent from reaching the surface. These data allow the optical depth representing the aerosol amount of coarse and fine radius groundbased sun photometry were made in bern, switzerland during two and a half years primarily to provide quantitative corrections for atmospheric effects in remotely sensed data in the visible and nearinfrared spectral region. Intercomparison of multisatellites and aeronet aod over. In this study, focusing on improving estimates of aerosol information on large scale, we develop a data synergy technique based on the ensemble kalman filter enkf to effectively combine these two types of measurements and yield a monthly mean aerosol optical depth aod product with global coverage and improved accuracy. Aerosol optical thickness is the degree to which aerosols prevent the transmission of light in the atmoshpere. Aerosol optical depth retrieval by neural networks. Esrl global monitoring laboratory global radiation group. Aerosol optical depth aod is a quantitative estimate of the amount of aerosol present in the.
Simulated aerosol optical depth with the large size mode improve the agreements with observations, especially in high. A geostatistical data fusion technique for merging remote. Merging aerosol optical depth aod and aod trend estimation from. The data records are merged on a daily basis by applying a state of the art quality. Importance of aerosol optical depth in the atmospheric. Pdf satellite instruments provide a vantage point for studying aerosol loading consistently over different regions of the world. This study analyzes the spatiotemporal variations of seasonal moderate resolution imaging spectroradiometer modis deep blue db aod at 550 nm from the aqua satellite over saudi arabia for the period 2002. Comparison of modis 3km and 10km resolution aerosol optical depth retrievals over land with airborne sunphotometer measurements during arctas summer 2008, atmos. This example showed how to create a histogram of calipso feature optical depth values for dust aerosols over the saharan desert with some basic quality screening.
The misr standard aerosol retrieval algorithm runs in an operational, fully automatic mode. Aerosol optical depth as a measure of particulate exposure using imputed censored data, and relationship with childhood asthma hospital admissions for 2004 in athens, greece gary higgs, 1 david a sterling, 2 subhash aryal, 3 abhilash vemulapalli, 3 kostas n priftis. In order to merge the fmf from satellite and groundbased products, the theoretical. Aerosol optical depth aod is the measure of aerosols e. Windblown dust, sea salts, volcanic ash, smoke from wildfires, and pollution from factories are all examples of aerosols. Trends in aerosol optical depth over indiantrends in aerosol optical depth over indian region. Aerosol optical depth from 2000 to 2019 gis english. Inversion of aerosol optical depth based on modis remote. Tiny solid and liquid particles suspended in the atmosphere are called aerosols. Aod trend estimation from multiple satellite missions for the last four decades. How to generate a histogram of calipso feature aerosol. Jpss assistt overview and star enterprise algorithm development.
Misr global aerosol optical depth validation based on two. New regression method to merge different modis aerosol. Elevated aerosol layers can contribute up to 60% of the total column optical depth. It reports aerosol optical thickness aot and aerosol type at 17. Longterm aerosol optical depth trend over iran and identification of. A comprehensive set of aerosol optical depth aod data, produced by a merger of aod product data from the moderate resolution imaging spectroradiometer. Modis dark target products collection 6 and onward to collection 7 robert levy nasagsfc.
Longterm groundbased measurements of aerosol optical depth. Index termsaerosol optical depth aod, aerosol robotic net work aeronet, bayesian, merging, moderate resolution imag. A geostatistical data fusion technique for merging remote sensing and ground. A method to determine atmospheric aerosol optical depth. Aerosol optical depth aerosol particle size volcanic ash mass loading.
Aerosol optical depth is a measure of the extinction of the solar beam by dust and haze. Aerosol optical depth measurements by means of groundbased sun photometry were made in bern, switzerland during two and a half years primarily to provide quantitative corrections for atmospheric effects in remotely sensed data in the visible and nearinfrared spectral region. Aerosol optical depth and burden of sea salt aerosol with the large size mode are studied in community earth system model. The pacific ocean has a surface area of over 60 million square miles. This parameter see equation 1 can be calculated from two or more wavelengths using a least squares fit. However, factors such as human observation differences and local meteorological conditions often impair the spatial consistency of the visibility converted aod dataset. The optical depth due to extinction by the aerosol component of the atmosphere. Aerosols at ten sites in northwestern china are classified in this study. Pdf seasonal aerosol optical depth aod variability. Examples of aerosols include windblown dust, sea salts, volcanic ash, smoke from fires, and pollution from factories.
The constraints used in this method are 1 to require that the wavelength dependence of the aerosol optical thickness is a smooth nonlinear function of. In this paper, based on sensitivity of total dsr to aerosol physical optical parameters, a method is proposed to determine the 0. The remote sensing technology can accurate inverse the aerosol optical depth so as to demonstrate the haze distribution. Aod tells us how much direct sunlight is prevented from reaching the ground by these aerosol particles. Use of satellitebased aerosol optical depth and spatial clustering to predict ambient pm 2. The average depth of the pacific is 14,040 feet 4,280 meters. The size distribution of aerosols can be estimated from spectral aerosol optical depth, typically from 440nm to 870nm. The use of the term optical density for optical depth is discouraged. Impact of elevated aerosol layers on aerosol optical depth. Collection 6 edeep bluedark target comparison and merged aerosol products 1. The aerosol in the elevated layers had enhanced amounts of rbc, biomass burning aerosol, sulfate and nitrate. Merging regional and global aerosol optical depth records from major available satellite products. First longterm study on aod trend was evaluated over iran. Generally, aerosol optical depth aod is used as a proxy for the aerosol concentrations in a vertically distributed column in the atmosphere koren et al.
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